For DIY repair:
In your pic, the stitching that holds the 'cord' in its sleeve in the 'front most' portion is missing - A good indicator that the entire run of stitching is weak. The usual course is to totally replace the entire "Continuous Support Tape".
To replace the Continuous Support Tape ..... sailrite.com/easearch#!&ea_q=luff%20support%20tape ..... needs to be 'sized' to the exact furling foil .... by model number designation of the foil.
The sewing has to be precise ... or you can alter the 'shape' of the sail when flown.
If your sewing machine is 'strong enough' to 'punch' through several layers of the reinforcing patches in the tack and head 'corners', replace the entire support tape.
If not strong enough (you have a 'dressmakers' sewing machine) - use a 'ball point' needle and V69 polyester sail thread and replace only the existing support tape
between the reinforcement patches .... adding a lot of extra binding stitches at the ends on the SAIL to keep the ends in place. For the old support tape still attached to the area of the reinforcing patches - do NOT cut the
stitches that hold the tape to the sail, cut away the all the tape that is in front of the stitching - the new support tape will be a bit 'shorter', will only be BETWEEN the patches; but, should work just as well for this sized jib.
Spraying the polyester thread with a teflon dry lubricant during sewing will help keep the stitching consistent, even, and help prevent the 'foot' of the sewing machine from 'jumping' when the needle is extracted out of the cloth .... set the foot pressure adjustment to FULL ON with a dressmakers type machine. Sew as SLOW as the dressmakers machine will go.
Spray/soak the surface of the thread spool often, spray the thread loaded 'bobbin' every time you reinstall.
List of 'stuff' that you'll need:
Search support tape
Search thread
Seamstick 3/8" Basting Tape (50 Yds) basting tape
Use a 'ballpoint' sewing machine needle of the
correct size for V69 thread .... look up the 'thread to needle match' data on the Sailrite website - use the recommended needle size based on YOUR machine, not the Sailrite data.